The following background information is provided to assist the reader to understand the environment in which the invention will typically be used. The terms used herein are not intended to be limited to any particular narrow interpretation unless specifically stated otherwise in this document.
Powered door systems have been extensively utilized in various vehicle applications. Specifically, it is well known in the transit vehicle art to employ a door system having a powered door drive means and a lock mechanism for locking at least one door connected to such powered door drive means and driven thereby to at least partially cover and uncover a door portal aperture in the transit vehicle. Door systems, generally used, are of a sliding, pocket sliding, swing, or swing/sliding combination type. Lock mechanisms employed are generally either of a powered type, employing a solenoid or a cylinder as a lock/unlock mover, or of an over center type depending on the specific requirements. During locking movement, a first locking member mounted on the door or on its carrying member engages a second locking member stationaryly disposed within such lock mechanism, to be restrained from movement while the door is in the substantially closed and locked position and, more importantly, prevent such door from movement in the opening direction. Such lock mechanisms are taught, for example, in U.S. Pat. No. 6,139,073; U.S. Pat. No. 5,927,015; and U.S. Pat. No. 5,280,754; all owned by the assignee of the present invention. The teachings of U.S. Pat. No. 6,139,073; U.S. Pat. No. 5,927,015; and U.S. Pat. No. 5,280,754 are incorporated herein by reference thereto.
An alternative configuration of the lock mechanism allows the door to be closed and locked in, what is well known, a pushback mode. In the pushback mode, a second locking member disposed within the lock mechanism is adapted with a second locked position and a third locked position. The second and third locked positions are spaced apart by a predetermined distance. The door is considered at least partially closed, in terms that it cannot be manually opened to its full open position, when the first locking member passes such third locked position.
However, the door is enabled to be manually moved in the opening direction between the second and third locked position to enable the riding patron to withdraw an object or a garment trapped between mating door edges. This manual movement does not require an action by a drive element disposed within powered door drive means and generally does not provide a signal to the control system of the transit vehicle. After a predetermined time interval the door is commanded to substantially close and lock, at which point the first locking member passes the second locked position preventing any substantial door movement. Such lock mechanisms are taught in U.S. Pat. No. 6,282,970 and U.S. Pat. No. 6,032,416 owned by the assignee of the present invention. The teachings of U.S. Pat. No. 6,282,970 and U.S. Pat. No. 6,032,416 are incorporated herein by reference thereto.
Alternatively, the lock mechanism design may allow the door to be continually in the pushback mode during the transit vehicle movement in which case, the door is allowed to be manually moved in the opening direction until the first locking member reaches the third locked position. A well-known means of achieving continuous pushback is to incorporate a mechanical spring disposed either within the lock mechanism or between the drive nut and the door.
However, the significant disadvantage of the spring pushback is unrestricted and undesirable incremental longitudinal movement of the door during transit vehicle motion, particularly, as the spring fatigues over time. This undesirable movement compromises the sealing capabilities of the door system.
It is of utmost importance to maintain sufficient sealing engagement between adjacent doors disposed within door portal opening or between a single door and the mating edge member of the door portal opening. It is well known that rubber elements, otherwise known as sealing means, which are attached to the mating leading edges of each door, or a door and door portal edge provide the best sealing protection from outside environmental factors, such as moisture, noise and dust, penetrating the interior of the moving transit vehicle. Generally, surfaces of such mating rubber edge elements are in close proximity to each other to minimize the gap between rubber edge elements and, on many installations, such surfaces are in substantial contact with each other. Additional compression of the rubber edge elements is employed to maintain such contact and further to prevent vibration of the door system due to component and assembly tolerances and mechanical wear as the door system ages.
The difficulties of such an arrangement lie in that the lock mechanism must overcome additional frictional forces during locking and unlocking sequences. Tolerances of the rubber edge elements, general door system tolerances and environmental factors affect the engagement between such rubber edge elements resulting in either a frequent need for lock mechanism adjustments and fine tuning, decreased sealing capabilities, or decreased reliability of the lock mechanism operation.
As it can be seen from the above discussion, there is a need to enable sufficient sealing capabilities of the mating rubber edge elements while at least one door is in the closed and locked position without compromising the operation of the lock mechanism.
For passenger safety reasons, some Transit Authorities mandate that during transit vehicle motion the door cannot be manually opened upon actuation of the interior emergency release until the transit vehicle reaches a predetermined speed, typically under 3 miles per hour, generally referred to as zero speed.
The resulting zero speed signal which is produced by a speed sensor within the propulsion system of such transit vehicle is transmitted to the door system via the specially designated trainlines of such transit vehicles. Such mandate is best met with the lock mechanisms of the powered type due to presence of the powered unlock mover and its interface with such trainlines of the transit vehicle enabling positive locking of the first locking member. Yet, the door must be opened regardless of the speed if the exterior emergency release is actuated so that emergency personnel can ingress the vehicle from outside in case of emergency.
Further, as a general requirement related to passenger safety, the door system of the transit vehicle must contain redundancy within the locking arrangement so as to prevent unintentional door opening due to a single point failure within such locking arrangement. Furthermore, it is preferred, that such single point failure must be detectable by the control system of the transit vehicle.
Therefore, there is a need to provide a locking arrangement that meets operational safety requirements and enables sufficient sealing capabilities of the door system.
The U.S. Pat. No. 6,189,285, One- Or Two-Leaf Sliding Door, Swinging Door or Pocket Door, discloses a door system wherein the locking of the door is achieved without the use of the over center or solenoid type lock mechanisms. As illustrated in FIG. 5, the locking arrangement consists of a complex clutch (24-28) or brake in combination with a freewheel (23) which is mounted on the spindle (12) disposed within a powered door drive. The freewheel (23) is disposed at the first end of the spindle (12) and connected to a clutch or a brake via a receptacle (22). The freewheel, essentially, enables rotation of the spindle (12) in the closing direction without disengagement with the clutch (24-28). The clutch (24-28) controls rotation of the spindle (12) in the opening direction.
A drive element (10) enabling spindle (12) rotation and, more importantly enabling door (1, 2) movement, is disposed at the distal end of the spindle (12). The special arrangement of the freewheel (23) and brake results in a final closing position region in which the door (1, 2) is secured against unwanted opening instead of the fixed final closing position determined by the over center or solenoid type lock mechanisms. This results in a substantial simplification in assembly because, for example, there is no longer any need to allow for rubber seals of varying width to achieve required sealing against environmental factors.
The receptacle (22), when held in a stationary condition with respect to spindle (12) rotation, enables rotation of the spindle (12) in the closing direction. In order to open the doors (1, 2), the receptacle (22) must be released and enabled to rotate with the spindle (12). This is achieved by electrical release of the clutch (24-28) enabling the release of the disk (25) from engagement with counter disks (27, 28) which are disposed within the clutch and further enabling rotation of the shaft (24) and the receptacle (22) which is integral with shaft (24) with respect to the rotation of the spindle (12) in the opening direction.
In the emergency condition, manual opening of the door (1, 2) is enabled via a Bowden cable (15) attached to the rod (14) at one end and attached to the manual release handle at the distal end. Actuation of the cable (15) displaces rod (14) enabling release of the clutch (24-28) via a swiveling cam (not shown) so that disk (25) connected to shaft (24) is likewise released.
There are several disadvantages to the prior art design disclosed in U.S. Pat. No. 6,189,285. In the first aspect, the prior art design requires the use of the freewheel (23) and receptacle (22), in addition to clutch (24-28) and brake, as essential elements, to achieve locking and unlocking of the door (1, 2). Such components increase the complexity and cost of the door system and reduce its reliability.
In a second aspect, failure of the clutch mechanism, or failure of the freewheel (23), or failure of the receptacle (22), which are all single point failures, may create a hazardous condition wherein the spindle (12) unintentionally rotates in the opening direction and, more importantly, the door (1, 2) opens unintentionally during transit vehicle movement due to normal vibration, vehicle deceleration and acceleration or the patron leaning against the door (1, 2) thus enabling its movement in the opening direction.
The disclosure does not teach means for detecting and annunciating such failures. Additionally, the adaptation of the roller (18) and a stop surface (17) provides locking redundancy only in the case of a swinging or swinging/sliding combination door type and not in the case of the sliding type, particularly, of the pocket configuration, as those skilled in the art will appreciate that such roller (18) will be disposed within the path of the sliding door (1, 2), thereby preventing its full movement. Adaptation of the prior art design to enable roller (18) to disengage from the door (1, 2) prior to opening movement will result in a presence of the mechanical lock mechanism (or a dead-center mechanism) that the prior art claims to have eliminated. Therefore, the prior art design does not provide locking redundancy in preventing unintentional opening of the door (1, 2) of the sliding or sliding pocket type.
In a third aspect, the described locking arrangement does not provide for combination of locking the door (1, 2) in the pushback mode and enabling claimed sealing advantages due to presence of the freewheel (23) and receptacle (22). A spring loaded link arrangement may be fitted between the drive nut (21) and the door (1, 2) enabling pushback thereof. However, as was aforementioned, such spring loaded link arrangement will negate the adaptation of the clutch (24-28), or brake, to achieve desirable sealing by enabling incremental longitudinal movement of the door (1, 2) which is independent from the action of the clutch (24-28).
As it can be seen from the above discussion, there is a further need to enable sufficient sealing capabilities while at least one door is in the closed and locked position without compromising the safety of the door system operation and providing for a pushback operation.